A well-known form of harvesting machine is a rotary combine. A typical combine includes a crop harvesting apparatus which reaps grain stalks and other plant materials and feeds them to a separating or threshing apparatus. The grain stalks or other crop and plant materials harvested in the field are moved rearwardly from a crop harvesting header assembly and introduced for threshing to the rotor assembly by a crop feeder assembly.
In a rotary combine, the rotor assembly includes a generally tubular rotor housing mounted in the combine body. A driven rotor is coaxially mounted within the housing. The rotor comprises an infeed or inlet section and a cylindrical threshing section, and is supported at opposite ends by front and rear bearing assemblies.
The cylindrical threshing section of the rotor and the rotor housing mount cooperating threshing elements, which separate grain from other material in a threshing zone. The crop material is threshed as it spirals around the rotor threshing section and passes through openings in the rotor housing.
As discussed in Tanis U.S. Pat. No. 5,387,153, assigned to the same assignee as the present invention, the ability to transfer crop materials from the feeder assembly to the threshing zone of the rotor assembly is a key to efficient combine operations. Most rotary combine rotors include an infeed or inlet section impeller comprised of a series of impeller blades or flights arranged at a forward end of the rotor. The impeller flights rotate within a housing which is a part of the rotor housing. During harvesting operations, the generally linear movement of the crop materials received from the feeder assembly is converted by the rotating impeller flights into a rotating, circulatory movement, in a rearward and outward direction.
When rotary combines are used on certain long-stemmed leguminous or grassy crops, such as windrowed perennial or annual rye grass, clover, and bent grass, and oats, there is a potential for portions of such grassy crops and other plant materials such as weeds to extend into the impeller flights while other portions remain partially engaged with the feeder assembly. The latter portions tend to move toward the axis of rotation of the rotor assembly, and may wrap about the front rotor bearing or shaft. This can rob power and cause damaging heat build up around the bearing, potentially causing premature failure thereof.
Long-stemmed leguminous or grassy crops also have a tendency to wrap around or “hairpin” about the leading edge of the impeller blades or flights. This hairpinning action can create a buildup of crop materials on the aforementioned leading edge, which reduces the effectiveness of the impeller and further reduces combine efficiency.
Numerous front rotor inlet and bearing housing designs, including that disclosed in the above referenced Tanis patent, have been proposed to prevent crop materials from becoming entangled with the front rotor bearing and prevent hairpinning about the impeller blades' leading edges. None has been thoroughly successful in doing so, however.
Tanis U.S. Pat. No. 6,296,566, also assigned to the same assignee as the present invention, discloses an infeed impeller for a rotary combine which utilizes anti-winding vanes on the rotor which cooperate with vanes on the front bearing assembly to force debris radially outwardly away from the axis of the rotor. However, this combination has been found to also suffer from the above-discussed shortcomings, more particularly, that long, particularly wet, crop material winds onto the rotor shaft which creates heat, consumes power, and causes early bearing failures. Additionally, hairpinning of such long grassy crop material about the leading edges of the impeller blades or flights can result in irregular wear in the form of scalloping of the leading edges, which can impede smooth flow of crop material radially outwardly along the leading edges.
Accordingly, what is sought is a front bearing housing anti-wind element and/or front rotor inlet section which provides improved anti-wind characteristics, particularly with regard to long, wet straw and other crop material.